page_title: Yagi–Uda antenna
hierarchical_section_title: Yagi–Uda antenna
caption_attribution_description: FuG 220 and FuG 202 (center) "Lichtenstein" night fighter radar equipment on the nose of a Messerschmitt Me 110 G-4 being serviced by German Air Force (Luftwaffe) ground crew on Grove airfield, Denmark, in August 1945, before the aircraft was sent to the UK for research.
context_page_description: A Yagi–Uda antenna, commonly known as a Yagi antenna, is a directional antenna consisting of multiple parallel elements in a line, usually half-wave dipoles made of metal rods. Yagi–Uda antennas consist of a single driven element connected to the transmitter or receiver with a transmission line, and additional "parasitic elements" which are not connected to the transmitter or receiver: a so-called reflector and one or more directors. It was invented in 1926 by Shintaro Uda of Tohoku Imperial University, Japan, with a lesser role played by his colleague Hidetsugu Yagi.
  The reflector element is slightly longer than the driven dipole, whereas the directors are a little shorter. The parasitic elements absorb and reradiate the radio waves from the driven element with a different phase, modifying the dipole's radiation pattern. The waves from the multiple elements superpose and interfere to enhance radiation in a single direction, achieving a substantial increase in the antenna's gain compared to a simple dipole.
  Also called a "beam antenna", or "parasitic array", the Yagi is very widely used as a high-gain antenna on the HF, VHF and UHF bands.
context_section_description: A Yagi–Uda antenna, commonly known as a Yagi  antenna, is a directional antenna consisting of multiple parallel elements in a line, usually half-wave dipoles made of metal rods. Yagi–Uda antennas consist of a single driven element connected to the transmitter or receiver with a transmission line, and additional "parasitic elements" which are not connected to the transmitter or receiver: a so-called reflector and one or more directors. It was invented in 1926 by Shintaro Uda of Tohoku Imperial University, Japan, with a lesser role played by his colleague Hidetsugu Yagi.                               
  The reflector element is slightly longer than the driven dipole, whereas the directors are a little shorter. The parasitic elements absorb and reradiate the radio waves from the driven element with a different phase, modifying the dipole's radiation pattern.  The waves from the multiple elements superpose and interfere to enhance radiation in a single direction, achieving a substantial increase in the antenna's gain compared to a simple dipole.
  Also called a "beam antenna", or "parasitic array", the Yagi is very widely used as a high-gain antenna on the HF, VHF and UHF bands. It has moderate to high gain which depends on the number of elements used, typically limited to about 20 dBi, linear polarization, unidirectional (end-fire) beam pattern  with high front-to-back ratio of up to 20 dB. and is lightweight, inexpensive and simple to construct. The bandwidth of a Yagi antenna, the frequency range over which it has high gain, is narrow, a few percent of the center frequency, and decreases with increasing gain, so it is often used in fixed-frequency applications. The largest and best-known use is as rooftop terrestrial television antennas, but it is also used for point-to-point fixed communication links, in radar antennas, and for long distance shortwave communication by shortwave broadcasting stations and radio amateurs.
caption: Yagi arrays of the German FuG 220 radar on the nose of a late-World War II Messerschmitt 110 fighter aircraft.
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